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https://dev.mysql.com/doc/refman/8.0/en/partitioning-limitations-partitioning-keys-unique-keys.html
The rule governing this relationship can be expressed as follows: All columns used in the partitioning expression for a partitioned table must be part of every unique key that the table may have. In other words, every unique key on the table must ...
https://dev.mysql.com/doc/refman/8.0/en/get-diagnostics.html
If that is not the case, a GET STACKED DIAGNOSTICS when handler not active error occurs. This instance of GET DIAGNOSTICS assigns the SQLSTATE value and error message to the user variables @p3 and @p4: GET DIAGNOSTICS CONDITION 1 @p3 = ...(You can ... GET [CURRENT | STACKED] DIAGNOSTICS { statement_information_item [, statement_information_item] ...
https://dev.mysql.com/doc/refman/8.0/en/index-condition-pushdown-optimization.html
ICP can reduce the number of times the storage engine must access the base table and the number of times the MySQL server must access the storage engine. For InnoDB clustered indexes, the complete record is already read into the InnoDB buffer. The ... Index Condition Pushdown (ICP) is an optimization for the case where MySQL retrieves rows from a table using an ...
https://dev.mysql.com/doc/refman/8.0/en/index-extensions.html
InnoDB automatically extends each secondary index by appending the primary key columns to it. Consider this table definition: CREATE TABLE t1 ( i1 INT NOT NULL DEFAULT 0, i2 INT NOT NULL DEFAULT 0, d DATE DEFAULT NULL, PRIMARY KEY (i1, i2), INDEX ...It also defines a secondary index k_d on column (d), but internally InnoDB extends this index and treats it as columns (d, i1, ...
https://dev.mysql.com/doc/refman/8.0/en/select-optimization.html
Queries, in the form of SELECT statements, perform all the lookup operations in the database. NDB Cluster supports a join pushdown optimization whereby a qualifying join is sent in its entirety to NDB Cluster data nodes, where it can be distributed ...Tuning these statements is a top priority, whether to achieve sub-second response times for dynamic web pages, or to chop hours off the time to generate huge overnight ...
https://dev.mysql.com/doc/refman/8.0/en/sys-schema-prerequisites.html
Before using the sys schema, the prerequisites described in this section must be satisfied. Because the sys schema provides an alternative means of accessing the Performance Schema, the Performance Schema must be enabled for the sys schema to work.
https://dev.mysql.com/doc/refman/8.0/en/json-validation-functions.html
If at least one of the arguments is not valid JSON, the function raises an error (ER_INVALID_TYPE_FOR_JSON) In addition, if the schema is not a valid JSON object, the function returns ER_INVALID_JSON_TYPE. The schema must be a valid JSON object; the ... Beginning with MySQL 8.0.17, MySQL supports validation of JSON documents against JSON schemas conforming to Draft 4 of the JSON Schema ...
https://dev.mysql.com/doc/refman/8.0/en/invisible-indexes.html
If an index made invisible actually is needed or used by the optimizer, there are several ways to notice the effect of its absence on queries for the table: Errors occur for queries that include index hints that refer to the invisible index. MySQL ...Dropping and re-adding an index can be expensive for a large table, whereas making it invisible and visible are fast, in-place ...
https://dev.mysql.com/doc/refman/8.0/en/multiple-tables.html
Given these considerations, the CREATE TABLE statement for the event table might look like this: mysql> CREATE TABLE event (name VARCHAR(20), date DATE, type VARCHAR(15), remark VARCHAR(255)); As with the pet table, it is easiest to load the initial ... The pet table keeps track of which pets you ...An event type ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-system-definition.html
Except when using NDB Cluster with MySQL Enterprise Monitor, is not necessary to have a [system] section in the config.ini file. The [system] section is used for parameters applying to the cluster as a whole. The Name system parameter is used with ...Name Version (or later) NDB 8.0.13 Type or units string Default [...] Range ...